ALSA: pcm: Don't call register and disconnect callbacks for internal PCM

The internal PCM (aka DPCM backend PCM) doesn't need any registration
procedure, thus currently we bail out immediately at dev_register
callback.  Similarly, its counterpart, dev_disconnect callback, is
superfluous for the internal PCM.  For simplifying and avoiding the
conflicting disconnect call for internal PCM objects, this patch drops
dev_register and dev_disconnect callbacks for the internal ops.

The only uncertain thing by this action is whether skipping the PCM
state change to SNDRV_PCM_STATE_DISCONNECT for the internal PCM is
mandatory.  Looking through the current implementations, this doesn't
look so, hence dropping the whole dev_disconnect would make more
sense.
Tested-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/pcm.c

@@ -775,6 +775,9 @@ static int _snd_pcm_new(struct snd_card *card, const char *id, int device,
 		.dev_register =	snd_pcm_dev_register,
 		.dev_disconnect = snd_pcm_dev_disconnect,
 	};
+	static struct snd_device_ops internal_ops = {
+		.dev_free = snd_pcm_dev_free,
+	};
 
 	if (snd_BUG_ON(!card))
 		return -ENXIO;
@@ -801,7 +804,8 @@ static int _snd_pcm_new(struct snd_card *card, const char *id, int device,
 	if (err < 0)
 		goto free_pcm;
 
-	err = snd_device_new(card, SNDRV_DEV_PCM, pcm, &ops);
+	err = snd_device_new(card, SNDRV_DEV_PCM, pcm,
+			     internal ? &internal_ops : &ops);
 	if (err < 0)
 		goto free_pcm;
 
@@ -1099,8 +1103,6 @@ static int snd_pcm_dev_register(struct snd_device *device)
 	if (snd_BUG_ON(!device || !device->device_data))
 		return -ENXIO;
 	pcm = device->device_data;
-	if (pcm->internal)
-		return 0;
 
 	mutex_lock(&register_mutex);
 	err = snd_pcm_add(pcm);
@@ -1159,12 +1161,10 @@ static int snd_pcm_dev_disconnect(struct snd_device *device)
 			snd_pcm_stream_unlock_irq(substream);
 		}
 	}
-	if (!pcm->internal) {
-		pcm_call_notify(pcm, n_disconnect);
-	}
+
+	pcm_call_notify(pcm, n_disconnect);
 	for (cidx = 0; cidx < 2; cidx++) {
-		if (!pcm->internal)
-			snd_unregister_device(&pcm->streams[cidx].dev);
+		snd_unregister_device(&pcm->streams[cidx].dev);
 		free_chmap(&pcm->streams[cidx]);
 	}
 	mutex_unlock(&pcm->open_mutex);